The prior art on tow bars and trailer hitches is prolific, and, much attention has been paid to the problem of providing removable bolt-on wheels for coupling to the sides of a boat to facilitate overland transportation and launching thereof. Brockelsby U.S. Pat. No. 3,986,723, for instance, discloses a removable wheel assembly for coupling a pair of rotatable wheels to a boat, thus to facilitate trailering or transportation by hand. In one embodiment the shaft holding the wheel has a groove around its circumference. This shaft fits through the side of the boat into a tubular socket member where it is engaged by a lock pin. The assembly allows the shaft to rotate but it retains it within the tubular socket against axial movement. The wheels are attachable in three positions to the bore, stability is provided by a U-shaped brace which attaches either forwardly or rearwardly of the assembly to provide alignment for the wheel. Other art is somewhat related with different means for attaching and moving the wheels for use on land or for positioning in an out-of-the-way position while the boat is in the water.